#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int, int> pii;

void solve() {
	int n;
	cin >> n;
	vector<int> a(n);
	for(int i = 0; i <n; i++) cin >> a[i];
	cout << *max_element(a.begin(), a.end()) - *min_element(a.begin(), a.end()) << endl;
}

signed main() {
	int t = 1;
	cin >> t;
	while(t--) solve();
	return 0;
}